This invention pertains to chains in general and in particular to chains used for removing the bark from logs by flailing or beating.
Chains attached to rotating drums or cylinders have proven to be an efficient means for removing bark from trees. However, these chains wear out quickly because of high stress from repeatedly striking wood and must be replaced frequently.
The present method of attaching the chains to the drum is to slip one link of the chain into a slot or hole in the drum and slide a rod through an opening in the drum parallel to the drum axis and through the chain link. A problem with this is that a number of chains are attached to each drum and not all of the chains may need to be replaced at the same time. Also the attachment rod itself may become deformed during use and it may be difficult to insert the rod through the drum when reattaching the new chain.
Changing flail chains is labor intensive and usually requires a two man crew. A man in the flail chamber positions new and rearranged chains in the rotor holes. A second man, on the outside of the flail debarker, reinserts the attachment rods through a small opening in the drum. Communication between the two men is necessary to avoid finger injuries. A two man crew can change and rearrange chains in about 30-45 minutes.
A major drawback to this chain servicing system is that not all the chains will normally need to be changed or rearranged. Flail chains also wear at different rates depending on their position on a rotor. Usually the chains attached to the center half of the drum will wear twice as fast as the chains attached near the end. The standard chain servicing system requires the attachment rods to be pulled completely out of the rotor to service the chains at the end of the rotor. Therefore, all the chains in a row have to be handled and reinserted in the rotor holes, even though some may be in good condition.
An additional problem with the debarking apparatus presently in use is that chains must be discarded before they are completely worn out. A new nine link chain may be used until it has lost an end link. The service crew may then flip the chain to wear the other end until it has lost two more links. The chain is then discarded because it is too short to effectively debark logs; however, it still has 5-6 good links.